This study was conducted to compare the characteristics of heat dissipated from LED lamps with water cooling method and natural cooling method in a closed-type plant production system (CPPS) and to determine the optimum water temperature and flow rate for LED lamps with water cooling method. The experiments were performed in CPPS maintained at temperature of 24℃ and humidity of 70%. As compared to the LED lamps operated at water temperature of 22.5±1.2℃and flow rate of 1,521±3.3 mL・min^(-1), air temperature under LED lamps with natural cooling was approximately increased by 1℃ and photosynthetic photon flux was decreased by 10 μmol・m^(-2)・s^(-1). PPF illuminated from LED lamps was affected by forward voltage varied by the surface temperature of LED lamps. Forward voltage of LED lamps was decreased with increasing surface temperature and then PPF was proportionately decreased. Five levels (14℃, 17℃, 20℃, 23℃, 26℃) of water temperature and three levels (500 mL・min^(-1), 1,000 mL・min^(-1), 1,500 mL・min^(-1)) of flow rate were provided to analyze the change of surface temperature and heat exchange of LED lamps. Heat exchange was increased with decreasing water temperature and increasing flow rate. At flow rate of 1,000-1,500 mL・min^(-1) and water temperature of 22.0-22.6℃, surface temperature of LED lamps can be approached to 24℃ that was almost same as air temperature in CPPS. The calorific value generated from LED lamps used in the study was estimated to be 103.0 kJ・h^(-1).